The present invention relates generally to a bed construction, and more particularly to a bed construction having a one-sided mattress assembly supported on a rigid foundation that offers significant reduction in the amount of permanent deflection or sagging of sleeping surface of the mattress.
A conventional inner spring mattress as known in the bedding industry generally comprises a resilient construction consisting of two sleep surfaces (a top layer and a bottom layer) enclosing an assembly of wire springs. The wire springs are typically covered with padding layers on the top and bottom surfaces, and the whole assembly is encased within a ticking, often quilted, that is sewn closed around its periphery to a border or boxing. For many years, one form of spring assembly construction has been known as Marshall construction. In Marshall construction, individual wire coils are each encapsulated in fabric pockets and attached together in strings which are arranged to form a closely packed array of coils in the general size of the mattress. Examples of such construction are disclosed in U.S. Pat. Nos. 685,160, 4,234,983, 4,234,984, 4,439,977, 4,451,946, 4,523,344, 4,578,834, 5,016,305 and 5,621,935, the disclosures of which are incorporated herein by reference in their entireties.
Conventionally, inner spring mattresses, with either pocketed coils or open coils, have had identical top and bottom layers. During normal life of such conventional mattresses some degree of permanent deflection, or sag, can develop in the mattress surfaces due to compaction of the component padding materials in the top and bottom layers. This permanent deflection can interfere with the mattresses""intended function of providing a supportive and resilient sleep surface. Inner spring mattress manufacturers recommend periodically rotating and turning over the mattress thereby utilizing the top and bottom sleep surfaces in order to counteract, minimize, and/or delay the aforementioned permanent deflection or sag. Under continued use, this compaction or sag becomes more permanent. The degree of permanent deflection is directly related to the type and amount of padding installed both over and under the wire spring core assembly. To remedy this shortcoming, manufacturers utilize materials that produce less permanent compaction. These materials are generally more dense but can be less comfortable and more expensive.
Conventional foundations, such as box springs, often contributed to the problem of sagging by providing a compressible top layer. Any additional compaction of the top layer of the foundation contributes to the overall sagging of the sleeping surface of the mattress.
Accordingly, it is desirable to provide a bed construction having an inner spring mattress assembly which exhibits a reduced amount of permanent deflection due to compaction of padding materials while at the same time exhibiting substantial comfort in use. It is further desirable to provide a mattress assembly that can be constructed by conventional known manufacturing techniques. Still further, it is desirable to provide a mattress assembly that is cost-effective to produce.
The present invention improves over the prior art by providing a bed construction with a one-sided mattress assembly supported on a rigid foundation. The one-sided mattress assembly includes a core of wire springs including, but not limited to, pocketed or open coil springs. The spring core of the mattress is covered by a layer of resiliently compressible material covering the upper sleeping surface thereof. The spring core of the mattress is supported on a bottom layer constructed of a substantially rigid material that is not generally compressible. The core of coil springs is attached to the bottom layer around its periphery. The rigid bottom layer of the mattress assures firm support for the coil springs and thereby reduces sagging that may result from the springs being poorly supported by the compressible padding under the springs of a conventional two-sided mattress.
In connection with the present invention, the padding for the top layer is selected to resist permanent compaction or deflection. Moreover, padding is only needed on the top layer of the mattress thereby reducing by one-half the amount of padding required. Consequently, the mattress construction of the present invention with a padded top layer and a rigid bottom layer necessarily reduces the amount of material that is subject to permanent compaction and therefore reduces the amount of permanent deflection of the mattress overall. Maintenance of the mattress of the present invention by rotating or turning the mattress over is also avoided.
In order to further reduce sagging of the sleeping surface of the mattress, a rigid foundation is provided to give further support to the rigid bottom layer of the one-sided mattress and therefore the spring core.